Synthesis and properties of photosensitive rubbers. IV. Photosensitive rubbers from hydroxyethyl cinnamate and polyisoprene modified with maleic anhydride

Abstract

SynopsisPolyisoprene in o-dichlorobenzene solution were reacted with maleic anhydride a t 180°C under nitrogez atmosphere to form modified polyisoprene with a-substituted succinic anhydride groups. These groups were converted by reaction with hydroxyethyl cinnamate in pyridine a t 25°C to cinnamate groups. Various amounts of cinnamate groups as photosensitive groups could be easily introduced into polyisoprene up to 75 mol % toward polyisoprene repeating units. Polymer glass transition temperatures of the products rose linearly from -7OOC for polyisoprene to 60°C with increasing amounts of the side groups. The solution viscosity of the products in chloroform decreased from 9.34 for polyisoprene to 0.77 with increasing amounts of the side groups. The photosensitivity of the polyisoprene, which is based on the photodimerization of the cinnamate groups, was higher than that of polypentenamer having cinnamate groups due to the interaction by the free carboxylic acids neighboring with the cinnamate groups. The photosensitivity of the cinnamate group was kinetically evaluated in terms of the dependence on the polymer glass transition temperature. The interaction by the free carboxylic acid groups in the polyisoprene reduced the dependence of the photosensitivity on the mobility of the polymer segments. Linear relationship between observed rate constants of the photodimerization and (Tuv -Tg + 50)-' was obtained and the slope of the line changed and became very small a t higher glass transition temperatures.

Ultraviolet-curable liquid natural rubber

“…The principle method to prepare a UV-curable elastomer is to introduce a UV-curable or photosensitive molecule into an elastomeric chain. Azuma et al 2 introduced cinnamic acid moieties into synthetic polyisoprene while D. Derouet et al 3 followed similar procedure for maleinized liquid natural rubber.…”

“…In the case of photocurable elastomers, it also was found that most of the scientists explored the photocrosslinking reaction by using these two techniques. [2][3][4][5][6] In general, polymerization reaction or formation of the carbon-carbon linkage system is an exothermic reaction and the heat released can be measured by a calorimeter. On irradiating photosensitive materials, the photopolymerization or photocrosslinking reaction that occurs will also lead to the evolution of heat.…”

UV-light induced crosslinking reaction of cinnamate natural rubbers: Effect of the spacer length, counter-ion nature, and content

“…4,5 It has been found that chains and present some characteristics of microphase separation. small variations in the polymer structure may promote expressive changes in chain mobility, 17,18 In the solid state, the behavior to be expected 5268 / 8E45$$5268 05-16-98 10:56:03 polaal W: Poly Applied …”

“…The maleic residues were then esterified behavior with chemical structure. [3][4][5] One of the with glycol cinnamates, giving rise to half-esters, features required to improve reactivity seems to in which the cinnamate groups were separated be chain mobility. In this regard, polydienes have from the main chain by segments of different lengths.…”